In order to meet the demand for wireless data traffic which has increased since the commercialization of a fourth generation (4G) communication system, efforts have been made to develop an improved fifth generation (5G) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a “beyond 4G network” or a “post long-term evolution (LTE) system”.
The 5G communication system is considered to be implemented in higher frequency (mm-Wave) bands (e.g., 60 GHz bands) so as to accomplish higher data rates. In order to reduce propagation loss of the radio waves and increase the transmission distance thereof, beamforming, massive multiple-input multiple-output (MIMO), full dimensional MIMO (FD-MIMO), array antenna, analog beamforming, and large scale antenna techniques are discussed in 5G communication systems.
Also, in 5G communication systems, technology development for improving a network of a system is underway based on evolved small cells, advanced small cells, cloud radio access networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, coordinated multi-points (CoMPs), reception-side interference cancellation, and the like.
Further, in the 5G system, hybrid frequency shift keying (FSK) and quadrature amplitude modulation (QAM) modulation (FQAM) and sliding window superposition coding (SWSC) as advanced coding modulation (ACM) schemes, and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as advanced access technology, have been developed.
In a wireless local area network (WLAN) system according to the Institute of Electrical and Electronics Engineers (IEEE) 802.11 standard, in a basic service set (BSS) which is based on a particular access point (AP), the AP or a particular station connected to the AP monopolizes an access right to a particular channel. As a result, when two or more nodes access a particular node, for example, when two or more stations transmit uplink signals, the stations need to sequentially transmit the uplink signals, which are intended to be transmitted, based on contention or scheduling. However, this transmission scheme serves as a factor, which reduces the overall performance of a WLAN system, since overhead becomes larger as the number of stations accessing to the particular channel increases.
Accordingly, a technique, which enables multiple users to transmit uplink signals through a particular channel, is introduced to a next-generation WLAN system. In order to enable multiple users to transmit the uplink signals through the particular channel, an AP may serve as a central controller and may schedule uplink transmissions by stations included in a BSS. At this time, the AP needs buffer status-related information in order to appropriately schedule the uplink transmissions by the stations. Each of the stations may also notify the AP of a demand for the uplink transmission, and may request the AP to allocate resources required for the uplink transmission.
To this end, the AP and each station may use a buffer status report (BSR) frame. The BSR frame serves as a kind of request to send (RTS) which allows each station to request permission for uplink transmission, and, serves to deliver buffer status-related information on each station. The BSR frame is transmitted in a transmission scheme which is based on one of a distributed coordination function (DCF), a point coordination function (PCF), and a power save multi-poll (PSMP).
A DCF-based transmission scheme signifies a scheme in which, when a station desiring transmission monitors a channel during a predetermined time period and detects an unused channel, the station accesses the relevant channel and transmits an uplink signal. However, in an environment where stations are densely located, multiple channels access the detected unused channel, so that a collision may frequently occur. When the collision occurs, according to the DCF-based transmission scheme, a backoff time period is lengthened and transmission is performed in order to reduce a collision occurrence probability, and thus it is problematic that a channel is wasted.
A PCF-based transmission scheme signifies a scheme in which an AP sequentially transmits a poll message to all stations within a BSS, inquires of each station whether each station desires to perform uplink transmission, and allocates uplink resources to a station, which desires to perform the uplink transmission, on the basis of a response message of each station to the poll message. As compared with the DCF-based transmission scheme, the PCF-based transmission scheme is advantageous in that a collision does not occur, but is problematic in that much time is required since it is necessary to sequentially poll all of the stations within the BSS.
A PSMP-based transmission scheme is a scheme in which an AP as a central controller secures channel resources during a predetermined time period, allocates the secured channel resources to multiple stations, and allows the stations to sequentially transmit uplink signals. The PSMP-based transmission scheme is different from the PCF-based transmission scheme in that the AP allocates resources to multiple previously-selected stations without polling stations, and enables each station to request the AP to additionally allocate resources in the form of a piggyback when each station transmits an uplink signal.
As described above, the DCF-based transmission scheme and the PCF-based transmission scheme require much time to collect BSR frames from multiple stations due to a backoff delay and polling, respectively, and thus are inefficient. Also, according to the PSMP-based transmission scheme, uplink transmission is performed based on scheduling by an AP without separate polling or buffer-related information of a station, and thus overhead caused by unnecessary resource allocation is inevitable.
Accordingly, there is a need for a method capable of efficiently transmitting a BSR frame even in an environment where stations are densely located.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.